docs: def os_requires_version(ostack_release, pkg):
      """
      Decorator for hook to specify minimum supported release
      """
      def wrap(f):
          @wraps(f)
          def wrapped_f(*args):
              if os_release(pkg) < ostack_release:
                  raise Exception("This hook is not supported on releases"
                                  " before %s" % ostack_release)
              f(*args)
          return wrapped_f
      return wrap